The present invention relates to a cartridge for an endless inked ribbon for typewriters and other printing office machines, comprising a container in which the ribbon is disposed in loops distributed at random and in which a section of the said ribbon is twisted through 180.degree. to form a Mobius loop.
An inked-ribbon cartridge is known in which the inked ribbon is not disposed in random loops but is twisted in a Mobius loop and is guided by a number of rotatable rollers inside the cartridge. An inking roller is kept in contact with the ribbon for the inking thereof and one of the rollers, which is spring actuated, acts as a ribbon tensioner and keeps the ribbon under tension. A section of the ribbon is twisted through 180.degree. and a wedge-shaped element bearing on the ribbon localises this section in a well-defined part of the cartridge and prevents the twisted section of ribbon being able to migrate to the section of the ribbon at which the striking action takes place. Owing to the presence of the inking roller, the rollers over which the ribbon runs and the ribbon tensioning roller, the cartridge is somewhat complicated and its cost is rather high.
Another inked-ribbon cartridge of the aforesaid type is also known in which the ribbon is disposed at random inside the cartridge and is unwound outside for a relatively long portion. Moreover, when the cartridge is mounted in the machine, the ribbon is twisted through 180.degree. for a predetermined distance in its course outside the cartridge by means of a pair of pins of the machine to produce the twist necessary for the Mobius loop. With this arrangement there is the disadvantage that, in addition to the normal guides for the ribbon, guide surfaces for the twist are present on the machine and the mounting of the cartridge thereon proves to be more complicated.